The Antimicrobial Activity of Cu/CuxO Composites Synthesized by Thermal Oxidation of Copper Tablets

Introduction: One of common bacteria is Staphylococcus aureus, which is a gram- positive, coagulasepositive, golden color in culture. That causes a wide range of clinical infections, resistance to β-lactam antibiotics. Objectives: In this paper, we investigate the ability of copper nanoparticles in Cu/CuxO composites to inhibit Staphylococcus aureus bacteria and the effect of oxidation temperature on the inhibition efficacy. Methods: Cu/CuxO composites were synthesized on the surfaces of copper samples by thermal oxidation of copper pressed tablets at various temperatures. The optical reflectivity spectra of the Cu/CuxO composites were measured. The edges of the plasma in these spectra were observed in the range 526-600 nm. In order to verify the antibacterial behavior of these composites, inhibition zone tests were realized for Staphylococcus aureus. Results: The results showed that, the widest zone of inhibition was for the treated sample at temperature 100°C. In addition, we found that the thermal oxidation reduces the ability of copper nanoparticles to inhibit bacteria. Conclusions: The results we obtained are summarized in the following points: 1) Thermal oxidation reduces the reflectivity of copper samples. 2) The plasma edge increases with the increase in the oxidation temperature. 3) Increasing the oxidation temperature leads to a decrease in bacterial inhibition rates.